Shop Buddy was built over 10 Saturdays by Junior Highschool
students as an extra curricular project. Shop Buddy is made
almost entirely from scavenged materials. The frame is a 55
gal. drum cart, the gear motors on the wheels are from junk
vending machines, the controller is a TRS-80 Color computer
from a thrift store. Shop Buddy has basic bump switches and
dual photo cells for light tracking and measuring. We have
also mounted a photo cell on a stepper motor to scan light
levels. A sound chip from a toy allows us to select different animal sounds at different occasions. In the works is IR whisker collision avoidance if we can boost the range to more than a few inches. An ultrasonic unit scrapped from a polaroid camera was attempted but the computer runs basic and I don't think the kids are up to the task of hand assembling 6809 code.

The TRS-80 Color computer contoller is a really great unit for the money (69 cents). It runs a Motorola 6809 processor at 1 mhz with 16 or 32 k ram. That doesn't sound like much but it also has built in extended Basic, keyboard, TV output, cassete tape interface, 4 channel 6 bit ADC,6 bit DAC, an extra rom socket, and a card edge connector which is a fully decoded parrallel bus. I have built simple I/O boards with one chip and power darlingtons to drive just about anything. The kids bolt on all kinds of electrical devices and experiment with control and feedback by
writing simple basic programs. I have several of these computers and boards set up so we can develop and test things before trying them on Shop Buddy. The kids have a blast gutting components out of old machines, then bolting things together in a new way and watching it drive around the parking lot doing what it does on its own.